[firebase_instllations] getId() throws _CastError Null check operator used on a null value

[mj-hd]

In my app, 500~600 users report a _CastError Null check operator used on a null value error at getId().

I'm using the getId() method in RootApp widget's initState function with a Future.microtask:

// this is a pseudo-code, I'm using flutter_hooks and useEffect actually
void main() {
  runApp(RootApp());
}

class RootApp extends StatefulWidget {
  ...
}

class RootAppState extends State<RootApp> {
  @override
  void initState() {
    super.initState();
    Future.microtask(() async {
      final installationId = await FirebaseInstallations.instance.getId();
      print(installationId);
    });
  }
}

The stack trace looks like this:

_CastError: Null check operator used on a null value
  File "method_channel_firebase_app_installations.dart", line 80, in MethodChannelFirebaseAppInstallations.getId
  File "<asynchronous suspension>"
  ...app code...

What situation may cause this error?